The present invention relates to digital image recording. Particularly, this invention relates to digital image recording of compressed digital image signals on a storage medium.
Well known video tape recorders record and reproduce image signals compressed and coded by a standard color moving picture compression and coding method such as MPEG on and from a magnetic tape via a rotary head mechanism.
The recorders are capable of recording data for special reproduction such as quick reproduction on specific locations on the magnetic tape under a fixed reproduction speed in special reproduction.
The special reproduction data includes data generated under a high compression ratio with low frequency component extraction. However, signals transmitted by digital TV broadcasting do not include such special reproduction data, thus special reproduction data recording and reproduction being impossible.
An object of the present invention is to provide an apparatus and a method of digital image signal recording capable of special reproduction of digital image signals with no special reproduction data.
The present invention provides an apparatus for recording a digital image signal, comprising: a separator to separate intraframe data from an input digital image signal compressed with orthogonal transform; a memory to store the separated intraframe data; a first generator to generate first data for special reproduction by reading the stored intraframe data at a frame interval depending on a reproduction speed and eliminating second data from the intraframe data read from the memory so that an amount of remaining data after the second data is eliminated is within a target code amount, the second data being related to orthogonally transformed block coefficients of the intraframe data read from the memory; and a second generator to generate data to be recorded by combining the first data for special reproduction with the input digital image signal.
Further, the present invention provides a method of recording a digital image signal, comprising the steps of: separating intraframe data from an input digital image signal compressed with orthogonal transform; storing the separated intraframe data in a memory; generating first data for special reproduction by reading the stored intraframe data at a first frame interval depending on a reproduction speed and eliminating second data from the intraframe data read from the memory so that an amount of remaining data after the second data is eliminated is within a target code amount, the second data being related to orthogonally transformed block coefficients of the intraframe data read from the memory; and generating data to be recorded by combining the first data for special reproduction with the input digital image signal.